I didn't even see HnNoPassMailer until I turned on showdead, and after I did I only saw an upvote link, not a downvote link. I think it's some feature of HN.
His/her last two comments seem to be dead, which might suggest he/she's been banned and has his/her comments now autodeaded. I don't see anything obvious in the comment/submission history that'd explain why there'd be a ban, but I don't really know how these things work.